A group of four investigators from the Department of Biology and the Department of Chemistry at MIT request funds for an analytical ultracentrifuge. This instrument will primarily be used to investigate molecular weights in aqueous solutions of oligopeptides, protein fragments, and oligosaccharides that have been developed as model systems. Because many of the model species undergo association, and because of difficulty in obtaining reliable molecular weights by chromatographic methods, an analytical centrifuge is essential. There is currently no analytical centrifuge in any laboratory on the MIT campus. The research projects that will use the analytical centrifuge include: motifs for the molecular recognition of transfer RNAs (P. Schimmel), structure-function relationships-of heparin proteoglycans (P. Lansbury, Jr.), protein dissection of protein folding and macromolecular recognition (P. Kim), and structure-function relationships of intestinal microvillus proteins (P. Matsudaira). The equipment will be housed in an. instrument room that is under the direct supervision of Professor Schimmel.